Barrichello: Don't Underestimate Williams

Brazilian Rubens Barrichello says Ferrari need to watch out for Williams at next week's Monaco Grand Prix.

"We should remember that last year, Williams did not really get on the pace until they won in Monaco," he told Ferrari's website. "So we should definitely not discount them and now it is clear that, in terms of pure speed, BAR are the closest to us, with Williams and Renault not too far behind."

Colombian Juan Pablo Montoya won in Monaco last year, ending a 20-year barren streak for Williams in the Mediterranean principality. That set the BMW-powered team on the road to recovery with three wins in the next five races after a disappointing start to the year.

By August they were looking favourites for both titles ultimately claimed by Ferrari and Michael Schumacher, who has won the first five races of this season in a record-equalling start that could continue for some time.

Although Williams chief operations engineer Sam Michael said at the weekend there was nothing to make him think his team would beat Ferrari in Monaco, Ferrari technical director Ross Brawn voiced concerns.

Qualifying is critical at Monaco, with overtaking very tricky on the twisty street circuit, and tyre performance likely to be a key factor. Ferrari use Bridgestone while their main rivals are on Michelin.

"We perhaps have a performance advantage on occasions but it may not be enough to overcome the first lap performance of the Michelins," said Brawn. "When we don't get a strong position at the beginning of the race we can't use the car.

"We've got a race coming at Monaco where it will be absolutely crucial and we've been doing a lot of things, we've got a lot of things happening in testing to try and give a very strong tyre for the first lap, even if that means a little less consistency."